locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE()

Please do not apply this to mainline directly, instead please re-run the
coccinelle script shown below and apply its output.

For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
preference to ACCESS_ONCE(), and new code is expected to use one of the
former. So far, there's been no reason to change most existing uses of
ACCESS_ONCE(), as these aren't harmful, and changing them results in
churn.

However, for some features, the read/write distinction is critical to
correct operation. To distinguish these cases, separate read/write
accessors must be used. This patch migrates (most) remaining
ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following
coccinelle script:

----
// Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and
// WRITE_ONCE()

// $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch

virtual patch

@ depends on patch @
expression E1, E2;
@@

- ACCESS_ONCE(E1) = E2
+ WRITE_ONCE(E1, E2)

@ depends on patch @
expression E;
@@

- ACCESS_ONCE(E)
+ READ_ONCE(E)
----

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: davem@davemloft.net
Cc: linux-arch@vger.kernel.org
Cc: mpe@ellerman.id.au
Cc: shuah@kernel.org
Cc: snitzer@redhat.com
Cc: thor.thayer@linux.intel.com
Cc: tj@kernel.org
Cc: viro@zeniv.linux.org.uk
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 6 insertions, 6 deletions

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index a1c24443cd9e..dab946554157 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -490,7 +490,7 @@ ip6_tnl_err(struct sk_buff *skb, __u8 ipproto, struct inet6_skb_parm *opt,
 	if (!t)
 		goto out;
 
-	tproto = ACCESS_ONCE(t->parms.proto);
+	tproto = READ_ONCE(t->parms.proto);
 	if (tproto != ipproto && tproto != 0)
 		goto out;
 
@@ -899,7 +899,7 @@ static int ipxip6_rcv(struct sk_buff *skb, u8 ipproto,
 	t = ip6_tnl_lookup(dev_net(skb->dev), &ipv6h->saddr, &ipv6h->daddr);
 
 	if (t) {
-		u8 tproto = ACCESS_ONCE(t->parms.proto);
+		u8 tproto = READ_ONCE(t->parms.proto);
 
 		if (tproto != ipproto && tproto != 0)
 			goto drop;
@@ -1233,7 +1233,7 @@ ip4ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 
-	tproto = ACCESS_ONCE(t->parms.proto);
+	tproto = READ_ONCE(t->parms.proto);
 	if (tproto != IPPROTO_IPIP && tproto != 0)
 		return -1;
 
@@ -1303,7 +1303,7 @@ ip6ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
 	u8 tproto;
 	int err;
 
-	tproto = ACCESS_ONCE(t->parms.proto);
+	tproto = READ_ONCE(t->parms.proto);
 	if ((tproto != IPPROTO_IPV6 && tproto != 0) ||
 	    ip6_tnl_addr_conflict(t, ipv6h))
 		return -1;
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 40d7234c27b9..3f30fa313bf2 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -606,7 +606,7 @@ static int udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 		 */
 
 		/* if we're overly short, let UDP handle it */
-		encap_rcv = ACCESS_ONCE(up->encap_rcv);
+		encap_rcv = READ_ONCE(up->encap_rcv);
 		if (encap_rcv) {
 			int ret;
 
@@ -1432,7 +1432,7 @@ void udpv6_destroy_sock(struct sock *sk)
 
 	if (static_key_false(&udpv6_encap_needed) && up->encap_type) {
 		void (*encap_destroy)(struct sock *sk);
-		encap_destroy = ACCESS_ONCE(up->encap_destroy);
+		encap_destroy = READ_ONCE(up->encap_destroy);
 		if (encap_destroy)
 			encap_destroy(sk);
 	}